I believe one of the new type 45's is also going to be off shore and a bunch of typhoons have been re-situated for better air support.

Seems to be some serious concern over a possible airbourne attack, the typhoons working with early warning radar should be able to reach anything long before reaching london, while the type 45 can monitor half of englands air space on its own.

With the thousands of troops moving into the area it does seem a little overkill.

But if the missiles are in London, wouldn't they be shooting the plane down....over London? I can't help but think that it could cause a great deal of casualties.

The Olympic venues would have a larger population density. Kinda like would you let a plane go down at the Superbowl or in a residential area. The destructive area of a crashed plane actually isn't that large so better to take it down from the higher density.

Obviously they it wouldn't be the best thing for your decor if a SAM was fired out of your upstairs window, but everyone understands that if that's deemed necessary it's really the least of our problems.